The present invention generally relates to electrochemical cells including cathode additives and more particularly to primary alkaline electrochemical cells having cathodes formed of manganese dioxide, a tin dioxide additive, and other cathode components.
Typical alkaline cells include a steel cylindrical can having a cathode comprising manganese dioxide as the active material and formed on the interior surface of the steel can, an anode comprising zinc and located in the center of the cell, a separator located between the anode and the cathode, and an alkaline electrolyte simultaneously contacting the anode, cathode, and separator. A conductive anode current collector is inserted into the anode active material and a seal assembly closes the open end of the steel can.
A primary goal in designing alkaline batteries is to increase the service performance of the cell. The service performance is the length of time for the cell to discharge under a given load to a specific voltage at which the cell is no longer useful for its intended purpose. One approach taken to increase service performance was to increase the interior volume of the cell in order to increase the amount of active materials within the cell. However, the commercial external size of the cell is fixed, thereby limiting the ability to increase the amounts of active materials within the cell. In order to accommodate more active materials within the cell while maintaining the external size of the cell, the steel label of the conventional alkaline cell has been replaced with one made of thinner metalized plastic film. Thus, the steel can may be enlarged to provide a greater internal volume. By switching to a thinner plastic film label, the service performance of a typical alkaline cell was significantly increased.
Another approach taken to increase the service performance of a cell is to utilize an anatase titanium dioxide as an additive to a cathode having manganese dioxide as the active material. Despite past increases in service performance, the need to find new ways to increase service performance remains the primary goal of cell designers.